GB689561A - Improvements in and relating to metallising processes and apparatus - Google Patents

Abstract

689,561. Metallising spray producers. SARGROVE ELECTRONICS, Ltd., and SARGROVE, J. A. Jan. 30, 1948 [Feb. 19, 1947], No. 4834/47. Class 69 (iii). A metallising spray gun 16 which is fed with compressed air controlled by a valve 27, has the metal for spraying fed in the form of a wire 28, by a drive pulley 29 driveri by a motor 30, co-operating with a backing pulley 32 which is held in operative position by a piston 34 only when the air supply is allowed to reach the gun, so that the metal wire is fed to the gun only when required. In the apparatus shown a gun or bank of guns is employed to spray a metal coating on radio panels 12 carried by a conveyer 10. When a panel reaches the spraying compartment 11 a photocell or other sensing device initiates action by a control unit 15 whereby the spray guns are started up and brought into action. A pilot jet 19 of easily ignited town gas is ignited by a spark plug 21 and in turn ignites the jet 16, the supplies of gas and air being released by electromagnetic valves 23, 25, 27, in the correct sequence. After a time interval sufficient to complete the spraying of one panel the gun is shut off in the correct sequence and left ready for the next cycle, if however a further panel arrives before this period has elapsed the spraying operation continues for a further period. The longitudinal motion of the conveyer traversing the panel at slow speed ensures uniform spraying in one direction, a linear rocking motion being applied to the gun in the vertical direction by a piston 39 driven by compressed air in double acting fashion. The rate of wire feed to the gun is monitored by a pulley 52 fitted with contacts 33 sending a regular series of pulses to the control unit 15 which if arriving within the permissible time interval keep the gun in operation. In the event of the wire feed becoming too slow the interval between the pulses from contacts 33 becomes too long to maintain the control unit in operation and the apparatus is shut down in correct sequence and an alarm indicator energised. The control unit 15 comprises a multiple stepping switch, for correct sequence of starting and stopping the various supplies of gas, &c., and a three-valve electronic circuit for commencing and timing the sequence of operations and for shutting down the apparatus in the event of failure of any of the essential supplies and in conditions necessary for successful production of sprayed panels on the conveyer 10. Specifications 570,877, [Group XXXV], 635,756 [Group XXXVII], and 689,563, [Group II], are referred to.